2006A&A...457..917B


C.D.S. - SIMBAD4 rel 1.7 - 2021.01.24CET01:30:54

2006A&A...457..917B - Astronomy and Astrophysics, volume 457, 917-926 (2006/10-3)

Physical properties of two compact high-velocity clouds possibly associated with the leading arm of the Magellanic system.

BEN BEKHTI N., BRUENS C., KERP J. and WESTMEIER T.

Abstract (from CDS):

We observed two compact high-velocity clouds HVC 291+26+195 and HVC 297+09+253 to analyse their structure, dynamics, and physical parameters. In both cases there is evidence for an association with the Leading Arm of the Magellanic Clouds. The goal of our study is to learn more about the origin of the two CHVCs and to use them as probes for the structure and evolution of the Leading Arm. We have used the Parkes 64-m radio telescope and the Australia Telescope Compact Array (ATCA) to study the two CHVCs in the 21-cm line emission of neutral hydrogen. The observations with a single-dish and a synthesis telescope allow us to analyse both the diffuse, extended emission as well as the small-scale structure of the clouds. We present a method to estimate the distance of the two CHVCs.The investigation of the line profiles of HVC 297+09+253 reveals the presence of two line components in the spectra which can be identified with a cold and a warm gas phase. In addition, we find a distinct head-tail structure in combination with a radial velocity gradient along the tail, suggesting a ram-pressure interaction of this cloud with an ambient medium. HVC 291+26+195 has only a cold gas phase and no head-tail structure. The ATCA data show several cold, compact clumps in both clouds which, in the case of HVC 297+09+253, are embedded in the warm, diffuse envelope. All these clumps have very narrow HI lines with typical line widths between 2 and 4km/s FWHM, yielding an upper limit for the kinetic temperature of the gas of Tmax=300K. We obtain distance estimates for both CHVCs of the order of 10 to 60kpc, providing additional evidence for an association of the clouds with the Leading Arm. Assuming a distance of 50 kpc, we get HI masses of 5.9x103M and 4.0x104M for HVC 291+26+195 and HVC 297+09+253, respectively.

Abstract Copyright:

Journal keyword(s): Galaxy: halo - ISM: clouds - ISM: structure - ISM: kinematics and dynamics - galaxies: Magellanic Clouds

Nomenclature: Table 1: [BBK2006] HVC 297+09+253 A (Nos A-T). Table 2: [BBK2006] HVC 291+26+195 A (Nos A-Q).

Simbad objects: 16

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Number of rows : 16

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME Magellanic Stream HVC 00 32 -30.0           ~ 833 1
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9656 1
3 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5826 1
4 NAME Magellanic Bridge HI 03 11 -77.5           ~ 347 1
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15122 1
6 NAME HVC Complex A HVC 08 36 +64.4           ~ 118 0
7 WV 225 HVC 09 20.2 -16 03           ~ 21 0
8 NAME Magellanic Leading Arm III reg 10 07 -37.0           ~ 15 0
9 NAME HVC Complex M HVC 10 48.2 +48 00           ~ 73 0
10 NAME Magellanic Leading Arm reg 11 26 -82.0           ~ 74 0
11 NAME Magellanic Leading Arm II reg 11 39 -46.0           ~ 17 0
12 HVC 297+09+253 ? 12 12 -53.           ~ 3 0
13 NAME Magellanic Leading Arm I reg 13 19 -73.0           ~ 15 0
14 NAME HVC Complex C HVC 16 34.8 +63 07           ~ 230 1
15 HVC 291+26+195 ? ~ ~           ~ 2 0
16 NAME Local Group GrG ~ ~           ~ 7142 0

    Equat.    Gal    SGal    Ecl

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2021.01.24-01:30:54

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